This report describes clinical, gross, histological findings and distant metastases from a gingival SCC that mimicked a chronic gingivitis and periodontitis in its early presentation in the right maxillary area of a six year old, mate Terrier dog. At necropsy, no maxillary teeth on all over the maxilla were observed and the right maxillary bone was completely destroyed. Greyish-brown or mostly reddish-brown ulcerated and irregular tumoral masses markedly invade this area and the mandible left side. Metastases to lungs, mediastinal lymph nodes, liver, kidneys and cerebellum were evidenced. Histologically, the metastatic and primary masses consisted of islands and cords with many intercellular bridges and intensely eosinophilic keratinized centers with well squamous differentiation. Strongly cytokeratin positive staining of tumoral cells revealed by immunohistochemistry confirmed the epithelial origin of the primary tumour and of its metastases. It was the first report of a well differentiated squamous cell carcinoma with distant metastases to cerebellum and liver in a dog.